1. Field of the Invention
The present invention relates generally to a buckle used with belts, garments, baggage's etc., and more particularly to a buckle comprising a pair of male and female coupling members, the male coupling member attached to one part of such an article and the female coupling member attached to the other part so that the coupling of the male and female coupling members makes the both parts connected to each other.
2. Description of the Prior Art
A typical example of a buckle described above is disclosed in Japanese Patent Laid-open Publication No. 5-91905. The disclosed plastic buckle is comprised of a pair of male and female coupling members, the male coupling member being insertable into the female coupling member. The female coupling member is composed of a pair of parallel spaced upper and lower plates defining there between a chamber. The upper plate has a circular through aperture formed there through. The lower plate has its central area cut away to provide a resilient engaging tongue. The resilient engaging tongue extends from the lower plate and normally projects inside the chamber. The male coupling member is comprised of a peripheral body having a central hole and a substantially circular button extending from the peripheral body so as to substantially fill up the central hole. The peripheral body has a locking step formed on the distal end thereof. When the male coupling member is inserted into the female coupling member, the locking step of the male coupling member comes into locking engagement with the tip of the locking tongue, and the circular button, under its own bias, comes into locking engagement with the circular aperture. To uncouple the male coupling member from the female coupling member, the circular button exposed in the circular aperture is simply depressed. The circular button, in turn, presses down the resilient engaging tongue against its resiliency, thereby bringing the resilient engaging tongue out of locking engagement with the locking step of the male coupling member. Now that the locking step of the male coupling member comes out of locking engagement with the resilient engaging tongue of the female member, the male coupling member can be pulled out of the chamber of the female coupling member.
Another example of a buckle of this type is disclosed in Japanese Design Registration No. 794905. This conventional buckle, likewise, is comprised of a male coupling member and a female coupling member for coupling engagement with the male coupling member. The male coupling member is comprised of an insert plate and a resilient locking tongue cut in the insert plate and projecting slantly upward by its own resiliency. The resilient tongue has a circular button formed thereon. The female coupling member is comprised of a pair of upper and lower plates defining therebetween a chamber for receiving the insert plate of the male coupling member. The upper plate of the female coupling member has a circular aperture formed centrally. To couple the male coupling member and the female coupling member, the insert plate of the male coupling member is inserted into the chamber of the female coupling member. The insert member is inserted into the chamber against the bias of the resilient tongue, until the circular button reaches the central circular aperture. At this moment, the circular button enters the central circular aperture of the female coupling member by the resiliency of the resilient tongue. To uncouple the male coupling member from the female coupling member, the circular button is depressed out of engagement with the circular aperture. Now that the circular button is no longer engaged with the circular aperture of the female coupling member, the insert plate of the male coupling member may be released from the chamber of the female coupling member.
These conventional buckles, however, suffer drawbacks.
When the first buckle is in coupled disposition, the male coupling member can rotate relative to the female coupling member in the plane of the buckle. However, the male coupling member and the female coupling member cannot rotate relative to each other in other directions, especially, perpendicularly to the plane of the buckle. Such a buckle is oftentimes used with a belt. When the belt having the buckle thereon is wrapped around the body of a wearer, the buckle is subjected to stresses exerted in various directions through the belt. If subjected to stresses tending to act in the plane of the buckle, the buckle can absorb the stresses by the male coupling member rotating relative to the female coupling member in the plane of the buckle. But, if subjected to stresses acting perpendicularly to the plane of the buckle, the buckle cannot absorb the stresses because the male and female coupling members cannot rotate relative to each other perpendicularly to the plane of the buckle. This will cause the wearer to feel uncomfortable whilst wearing the belt.
The second conventional buckle also has drawbacks. In order to facilitate coupling of the circular button with the circular aperture, the circular aperture of the female coupling member must be made greater in diameter than the circular button of the male coupling member. Since the curvature of the circular aperture differs from that of the circular button, the circular button contacts the circular aperture only at a point, when the former is coupled with the latter. As a result, the stresses tending to separate the male coupling member from the female coupling member concentrate upon that contact point, which is likely to cause the male coupling member to accidentally detach from the female coupling member or to deform that region of the circular button or circular aperture and even damage the buckle as a whole.